I am an experienced chew quitter. Every time I quit, I start thinking a month later "Geez, it was so easy to quit the last time, one little chew won't hurt me." A couple days pass, and I have a couple more. Before I know it I'm chewing 1.5 cans a day. I've done it at least 3 or 4 times over the past few years.
I myself quit last week again. I've got kids now, and I just picture their faces when I think about having a chew and it seems to be working so far.
The secret to not starting again seems to be "Not even once". Don't have one ever again, no matter how innocent it seems.